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H. H. GORDON. AUTOMATIC FLUX CONTROL FOR lGNlTlON SYSTEMS.

APPLICATION FILED NOV, 20, 191?.

1,41 ,933, v Patented Apr. 18, 1922.

variable magneto motive force.

UNITED STATES PATENT OFFICE.

HAYNER H. GORDON, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGINOR TOELEC- Tmc AUTO-LITE CORPORATION, or TOLEDO, 01110, A CORPORATION OFDELAWARE.

AUTOMATIC FLUX CONTROL FOR IGNITION SYSTEMS.

Specification of Letters latent.

Patented Apr. 18, 1922 To aZZ whom it may concern:

Be it known that I, HAYNER 'H. GORDON, a citizen of the United States ofAmerica, residing at Washington, in the District of Columbia, have madenew and useful Im-. provements in Automatic Flux Controls for IgnitionSystems, of which the following is a full and complete specification,reference being had to the accompanying drawing, which forms part ofthis specification.

This invention relates broadly to structure in which an electric currentis generated, or set up in a winding by subjecting the same to avariation in magnetic flux, and relates more particularly to theprovision of automatic means for regulating the rateof flux changeindependently of the means that produces the flux change.

This invention also relates more particularly to high tension magnetosof the type which comprise a high tension winding, and a low tension orChoke winding super-imposed upon a core which is subjected to a In suchstructure a flux change is impressed upon the core, which change has avariable rate which approaches asharp maximum twice each revolution ofthe rotor, in the usual two pole magneto. The flux change how-' ever isopposed by the choke winding, which is normally short circuited, andwhich as soon as a flux change tends to take place in the core, sets upa counter magneto motive force which tends to resist such change. Atpoints of maximum rate of impressed flux change the chbke winding issuddenly opened by some external means such as a circuit breaker and thehitherto repressed flux chan e is permitted to take place in the core,there y setting up a potential in the high tension winding with aconsequent breaking down of the spark gap to which the high tensionwinding is connected. The spark thus formed continues to burn in theform of an arc, for the breaking down of the spark gap has closed thehigh tension winding or circuit and the current flowing in this windinghas a regulative effect upon the flux change takingplace in the coil.

This type of magneto operates very satisfactorily at low or normalspeeds but when it operates at the extremely high rate of speed demandedin the modern eight or twelve cylinder motors the intensity of the fluxchange becomes so great as to cause overheating from eddy currents setup in the magneto core structure and from the high current density ofthe short circuited choke winding. Also in a magneto which isdeslgned'to give a good spark when starting, when rotated at theextremely high speed demanded, the spark becomes so hot that thesparking points of the plugs are soon burned out or become overheatedcausing pre-ignition, and in addition the counter magnetomotive forcesetup by the choke winding at extremely high speed causes seriouscomplications in the armature reaction of the magneto. The low tensionor make and break magneto is also subject to the same effect, its-actionbeing substantially the same as that just set forth, with the exceptionthat no high tension winding is used, the terminals of the low tensionor choke winding, being connected directly to the spark producingterminals.

It is the general object of this invention to provide a structure inwhich the time constant of an electrical circuit acts to auto,-matically regulate the magnetic flux change in a current producin coil,the flux regulatmg means being in ependent of the flux companyingdrawing, in which is shown one embodiment of the same. In the drawing acore 1 is connected to pole pieces 2 and 3, the core having woundthereon a primary or choke windin 5 and a secondary winding 6. The chokewinding 5 has one end gr0undedat 9, the other end of the same beingconnected to the ground at 10 through the interrupter mechanism 8 acrossthe terminals of which is connected the usual condenser 8 One end of thesecondary 6. is grounded at 9 the other end being connected to the sparkplug 7-. A magnetized rotor 4, the magnetic energy of which may eitherbe fun nished by electromagnetic or permanent magnetic means, revolvesbetween the ends of the pole pieces 2 and 3 and furnishes the means forproviding the variable .niagnetic motive force to cause a flux change totake place in the core 1.

Connecting the pole pieces 2 and 3 is a supplementary core 11, havingwound thereon a short circuited winding 12, the magnetic area of thecore 11 being easily regulated or controlled by means of a saw out 13.The Winding 12 should normally be so proportioned' in size of wire andnumber of turns as to have a larger time constant or electrical inertiathan the choke winding 5, but if desired any well known type ofregulative inductance may be employedin circuit with the winding 12;this could either be done by using a selective switch to vary the numberof turns in winding 12, or by using some form of external regulation.

The operation is as follows; As the magnetized rotor 4 revolves therewill be impressed upon the pole pieces 2 and 3 a variable flux changewhich will reach a sharp maximum twice each revolution of the rotor. Assoon as magnetic flux change tends to take place in the cores 1 and 11,the choke windings 5 and 12 on these respective cores immediately buildup in the cores a counter magneto motive force so that'very little fluxchange will take place in these cores. When the rotor 4; is in aposition to produce the maximum flux change the choke winding 5 isopened by means of the circuit breaker 8 and the hitherto repressed fluxchange is allowed to take place in the core which thereby sets up acurrent in the secondary winding 6 with a consequent spark at the sparkgap 7 As long as the maximum rate of flux change induced in the core isof relatively low value, the only flux change that will take place incore 11 will be approximately that suflicient to supply 12R loss of thewinding 12, the change of flux through core 11 being resisted. As therate of flux change increases, however, the maximum voltage useful incoil 12 to set up a current which in turn sets up a countermagneto-motive force cannot reach to such a high proportionate value. Alarger proportion of flux will therefore pass through the core 11, andthe higher the rate of speed at which the mag neto rotor 1 is driven thelarger the leakage of the flux through the core ll'will become,-

the core 11 thereby acting as a sort of safety valve for the magneticflux and automatically keeping the flux change in the core 1 withincertain limits, depending upon the relation between the inductance inthe choke winding circuit, and the coil 12.

Attention is also called to the. fact that at extremely high magnetospeeds the counter magneto motive force set up by the coil 12 will tendto reinforce the change taking place in the core 1, upon the opening ofthe circuit breaker 8 thereby giving to the closed magnetic circuitformed by the cores 1 and 11 and the pole pieces 2 and 3 sufficientenergy to properly function after the rotor has passed the maximum fluxchange in these positions.

This accumulative reinforcing action will also have a tendency tonegative the energy absorbing effect of the condenser 8 Vhat I claim is:

1. In a magneto, the combination with two pole pieces, and a source ofmagnetic energy, of a rotor adapted to set up a variable magnetic fluxin said pole pieces, a core connecting said pole pieces together, saidcore having wound thereon a choke winding, a supplementary coreconnecting said pole pieces together and a flux controlling winding uponsaid supplementary core, the time constant of said fiux controllingwinding being of greater value than the time constant of the chokewinding, the choke winding thereby functioning to prevent anysubstantial flow of magnetic lines of force through the supplementarycore when the rate of magnetic flux change in said pole pieces is belowa predetermined value.

2. In a magneto, the combination with two pole pieces and a source ofmagnetic energy, of a rotor adapted to set up a variable magnetic fluxin said pole pieces, a core connecting said pole pieces together, saidcore having wound thereon a secondary winding and a choke winding, asupplementary core connecting said pole pieces together, a shortcircuited flux controlling winding upon said supplementary core, thetime constant of said flux controlling winding being of greater valuethan the time constant of the choke winding.

S. In a system for the generation of electrical energy, the combinationwith a source of magnetic energy, of a core, a current producing windingupon said core, means for producing a variation of magnetic flux in saidcore, a magnetic leakage path subjected to said magnetic flux variationfor shuntinga portion of the magnetic flux around said core and awinding for controlling the resistivity of said leakage path to fluxvaria tion.

4. In an ignition system for internal conibustion engines, a sparkproducing winding, means operated by the engine for producing a periodicchange of magnetic flux in said core to energize said winding, amagnetic shunt path of fixed reluctance also subjected to the periodicmagnetic flux change for controlling the rate of flux change in saidcore, and a winding on said shunt path, said winding forming a portionof a circuit having a fixed time constant.

5. In an ignition system for an' internal combustion engine, thecombination of a core, windings upon said core, means producing avariation of magnetic flux in said core, a circuit interrupter driven insynchronism with the engine and connected in series with one of thewindings on said core, a condenser connected across the terminals of thecircuit interrupter, a magnetic leakage path of fixed reluctance forshunting a portion of the magnetic flux around said core,

and having wound thereon a windin of fixed time constant functioning torein orce the magnetic flux change in the core when the engine isrunning above a certain speed.

6. In an electrical system in combination, a winding, means forproducing a periodic change of magnetic flux at variable frequencies insaid core, a magnetic leakage path subjected to said periodic fluxchange for shunting a portion of the magnetic flux around said Winding,and means for rendering said leakage path more effective atpredetermined frequencies.

In testimony whereof I hereunto set my hand.

HAYNER H. GORDON.

